cregit-Linux how code gets into the kernel

Release 4.7 fs/super.c

Directory: fs
/*
 *  linux/fs/super.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  super.c contains code to handle: - mount structures
 *                                   - super-block tables
 *                                   - filesystem drivers list
 *                                   - mount system call
 *                                   - umount system call
 *                                   - ustat system call
 *
 * GK 2/5/95  -  Changed to support mounting the root fs via NFS
 *
 *  Added kerneld support: Jacques Gelinas and Bjorn Ekwall
 *  Added change_root: Werner Almesberger & Hans Lermen, Feb '96
 *  Added options to /proc/mounts:
 *    Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
 *  Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
 *  Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
 */

#include <linux/export.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/writeback.h>		/* for the emergency remount stuff */
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/backing-dev.h>
#include <linux/rculist_bl.h>
#include <linux/cleancache.h>
#include <linux/fsnotify.h>
#include <linux/lockdep.h>
#include "internal.h"


static LIST_HEAD(super_blocks);
static DEFINE_SPINLOCK(sb_lock);


static char *sb_writers_name[SB_FREEZE_LEVELS] = {
	"sb_writers",
	"sb_pagefaults",
	"sb_internal",
};

/*
 * One thing we have to be careful of with a per-sb shrinker is that we don't
 * drop the last active reference to the superblock from within the shrinker.
 * If that happens we could trigger unregistering the shrinker from within the
 * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we
 * take a passive reference to the superblock to avoid this from occurring.
 */

static unsigned long super_cache_scan(struct shrinker *shrink, struct shrink_control *sc) { struct super_block *sb; long fs_objects = 0; long total_objects; long freed = 0; long dentries; long inodes; sb = container_of(shrink, struct super_block, s_shrink); /* * Deadlock avoidance. We may hold various FS locks, and we don't want * to recurse into the FS that called us in clear_inode() and friends.. */ if (!(sc->gfp_mask & __GFP_FS)) return SHRINK_STOP; if (!trylock_super(sb)) return SHRINK_STOP; if (sb->s_op->nr_cached_objects) fs_objects = sb->s_op->nr_cached_objects(sb, sc); inodes = list_lru_shrink_count(&sb->s_inode_lru, sc); dentries = list_lru_shrink_count(&sb->s_dentry_lru, sc); total_objects = dentries + inodes + fs_objects + 1; if (!total_objects) total_objects = 1; /* proportion the scan between the caches */ dentries = mult_frac(sc->nr_to_scan, dentries, total_objects); inodes = mult_frac(sc->nr_to_scan, inodes, total_objects); fs_objects = mult_frac(sc->nr_to_scan, fs_objects, total_objects); /* * prune the dcache first as the icache is pinned by it, then * prune the icache, followed by the filesystem specific caches * * Ensure that we always scan at least one object - memcg kmem * accounting uses this to fully empty the caches. */ sc->nr_to_scan = dentries + 1; freed = prune_dcache_sb(sb, sc); sc->nr_to_scan = inodes + 1; freed += prune_icache_sb(sb, sc); if (fs_objects) { sc->nr_to_scan = fs_objects + 1; freed += sb->s_op->free_cached_objects(sb, sc); } up_read(&sb->s_umount); return freed; }

Contributors

PersonTokensPropCommitsCommitProp
dave chinnerdave chinner19776.95%650.00%
vladimir davydovvladimir davydov3513.67%325.00%
glauber costaglauber costa103.91%18.33%
tetsuo handatetsuo handa93.52%18.33%
konstantin khlebnikovkonstantin khlebnikov51.95%18.33%
Total256100.00%12100.00%


static unsigned long super_cache_count(struct shrinker *shrink, struct shrink_control *sc) { struct super_block *sb; long total_objects = 0; sb = container_of(shrink, struct super_block, s_shrink); /* * Don't call trylock_super as it is a potential * scalability bottleneck. The counts could get updated * between super_cache_count and super_cache_scan anyway. * Call to super_cache_count with shrinker_rwsem held * ensures the safety of call to list_lru_shrink_count() and * s_op->nr_cached_objects(). */ if (sb->s_op && sb->s_op->nr_cached_objects) total_objects = sb->s_op->nr_cached_objects(sb, sc); total_objects += list_lru_shrink_count(&sb->s_dentry_lru, sc); total_objects += list_lru_shrink_count(&sb->s_inode_lru, sc); total_objects = vfs_pressure_ratio(total_objects); return total_objects; }

Contributors

PersonTokensPropCommitsCommitProp
dave chinnerdave chinner9393.94%666.67%
glauber costaglauber costa33.03%111.11%
vladimir davydovvladimir davydov22.02%111.11%
konstantin khlebnikovkonstantin khlebnikov11.01%111.11%
Total99100.00%9100.00%


static void destroy_super_work(struct work_struct *work) { struct super_block *s = container_of(work, struct super_block, destroy_work); int i; for (i = 0; i < SB_FREEZE_LEVELS; i++) percpu_free_rwsem(&s->s_writers.rw_sem[i]); kfree(s); }

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PersonTokensPropCommitsCommitProp
jan karajan kara3050.00%125.00%
oleg nesterovoleg nesterov2643.33%250.00%
al viroal viro46.67%125.00%
Total60100.00%4100.00%


static void destroy_super_rcu(struct rcu_head *head) { struct super_block *s = container_of(head, struct super_block, rcu); INIT_WORK(&s->destroy_work, destroy_super_work); schedule_work(&s->destroy_work); }

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PersonTokensPropCommitsCommitProp
oleg nesterovoleg nesterov44100.00%1100.00%
Total44100.00%1100.00%

/** * destroy_super - frees a superblock * @s: superblock to free * * Frees a superblock. */
static void destroy_super(struct super_block *s) { list_lru_destroy(&s->s_dentry_lru); list_lru_destroy(&s->s_inode_lru); security_sb_free(s); WARN_ON(!list_empty(&s->s_mounts)); kfree(s->s_subtype); kfree(s->s_options); call_rcu(&s->rcu, destroy_super_rcu); }

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PersonTokensPropCommitsCommitProp
oleg nesterovoleg nesterov3145.59%125.00%
jan karajan kara2536.76%125.00%
al viroal viro1217.65%250.00%
Total68100.00%4100.00%

/** * alloc_super - create new superblock * @type: filesystem type superblock should belong to * @flags: the mount flags * * Allocates and initializes a new &struct super_block. alloc_super() * returns a pointer new superblock or %NULL if allocation had failed. */
static struct super_block *alloc_super(struct file_system_type *type, int flags) { struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); static const struct super_operations default_op; int i; if (!s) return NULL; INIT_LIST_HEAD(&s->s_mounts); if (security_sb_alloc(s)) goto fail; for (i = 0; i < SB_FREEZE_LEVELS; i++) { if (__percpu_init_rwsem(&s->s_writers.rw_sem[i], sb_writers_name[i], &type->s_writers_key[i])) goto fail; } init_waitqueue_head(&s->s_writers.wait_unfrozen); s->s_bdi = &noop_backing_dev_info; s->s_flags = flags; INIT_HLIST_NODE(&s->s_instances); INIT_HLIST_BL_HEAD(&s->s_anon); mutex_init(&s->s_sync_lock); INIT_LIST_HEAD(&s->s_inodes); spin_lock_init(&s->s_inode_list_lock); if (list_lru_init_memcg(&s->s_dentry_lru)) goto fail; if (list_lru_init_memcg(&s->s_inode_lru)) goto fail; init_rwsem(&s->s_umount); lockdep_set_class(&s->s_umount, &type->s_umount_key); /* * sget() can have s_umount recursion. * * When it cannot find a suitable sb, it allocates a new * one (this one), and tries again to find a suitable old * one. * * In case that succeeds, it will acquire the s_umount * lock of the old one. Since these are clearly distrinct * locks, and this object isn't exposed yet, there's no * risk of deadlocks. * * Annotate this by putting this lock in a different * subclass. */ down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); s->s_count = 1; atomic_set(&s->s_active, 1); mutex_init(&s->s_vfs_rename_mutex); lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key); mutex_init(&s->s_dquot.dqio_mutex); mutex_init(&s->s_dquot.dqonoff_mutex); s->s_maxbytes = MAX_NON_LFS; s->s_op = &default_op; s->s_time_gran = 1000000000; s->cleancache_poolid = CLEANCACHE_NO_POOL; s->s_shrink.seeks = DEFAULT_SEEKS; s->s_shrink.scan_objects = super_cache_scan; s->s_shrink.count_objects = super_cache_count; s->s_shrink.batch = 1024; s->s_shrink.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE; return s; fail: destroy_super(s); return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
linus torvaldslinus torvalds9124.53%49.09%
al viroal viro6316.98%36.82%
dave chinnerdave chinner6216.71%715.91%
andrew mortonandrew morton184.85%24.55%
arjan van de venarjan van de ven154.04%24.55%
roland dreierroland dreier133.50%12.27%
vladimir davydovvladimir davydov133.50%36.82%
glauber costaglauber costa102.70%12.27%
ingo molnaringo molnar82.16%24.55%
william lee irwin iiiwilliam lee irwin iii82.16%12.27%
stephen d. smalleystephen d. smalley82.16%12.27%
david howellsdavid howells71.89%12.27%
neil brownneil brown71.89%12.27%
christoph hellwigchristoph hellwig61.62%24.55%
kentaro makitakentaro makita61.62%12.27%
oleg nesterovoleg nesterov61.62%12.27%
jan karajan kara61.62%24.55%
andi kleenandi kleen61.62%12.27%
dan magenheimerdan magenheimer51.35%12.27%
jens axboejens axboe41.08%12.27%
peter zijlstrapeter zijlstra30.81%12.27%
miklos szeredimiklos szeredi20.54%12.27%
nick pigginnick piggin10.27%12.27%
alexey dobriyanalexey dobriyan10.27%12.27%
greg kroah-hartmangreg kroah-hartman10.27%12.27%
oliver neukumoliver neukum10.27%12.27%
Total371100.00%44100.00%

/* Superblock refcounting */ /* * Drop a superblock's refcount. The caller must hold sb_lock. */
static void __put_super(struct super_block *sb) { if (!--sb->s_count) { list_del_init(&sb->s_list); destroy_super(sb); } }

Contributors

PersonTokensPropCommitsCommitProp
andrew mortonandrew morton2264.71%120.00%
al viroal viro1029.41%360.00%
kirill korotaevkirill korotaev25.88%120.00%
Total34100.00%5100.00%

/** * put_super - drop a temporary reference to superblock * @sb: superblock in question * * Drops a temporary reference, frees superblock if there's no * references left. */
static void put_super(struct super_block *sb) { spin_lock(&sb_lock); __put_super(sb); spin_unlock(&sb_lock); }

Contributors

PersonTokensPropCommitsCommitProp
linus torvaldslinus torvalds1864.29%240.00%
al viroal viro725.00%240.00%
andrew mortonandrew morton310.71%120.00%
Total28100.00%5100.00%

/** * deactivate_locked_super - drop an active reference to superblock * @s: superblock to deactivate * * Drops an active reference to superblock, converting it into a temporary * one if there is no other active references left. In that case we * tell fs driver to shut it down and drop the temporary reference we * had just acquired. * * Caller holds exclusive lock on superblock; that lock is released. */
void deactivate_locked_super(struct super_block *s) { struct file_system_type *fs = s->s_type; if (atomic_dec_and_test(&s->s_active)) { cleancache_invalidate_fs(s); unregister_shrinker(&s->s_shrink); fs->kill_sb(s); /* * Since list_lru_destroy() may sleep, we cannot call it from * put_super(), where we hold the sb_lock. Therefore we destroy * the lru lists right now. */ list_lru_destroy(&s->s_dentry_lru); list_lru_destroy(&s->s_inode_lru); put_filesystem(fs); put_super(s); } else { up_write(&s->s_umount); } }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro4044.94%327.27%
vladimir davydovvladimir davydov1719.10%19.09%
linus torvaldslinus torvalds1213.48%327.27%
dave chinnerdave chinner88.99%19.09%
david chinnerdavid chinner77.87%19.09%
dan magenheimerdan magenheimer55.62%218.18%
Total89100.00%11100.00%

EXPORT_SYMBOL(deactivate_locked_super); /** * deactivate_super - drop an active reference to superblock * @s: superblock to deactivate * * Variant of deactivate_locked_super(), except that superblock is *not* * locked by caller. If we are going to drop the final active reference, * lock will be acquired prior to that. */
void deactivate_super(struct super_block *s) { if (!atomic_add_unless(&s->s_active, -1, 1)) { down_write(&s->s_umount); deactivate_locked_super(s); } }

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PersonTokensPropCommitsCommitProp
al viroal viro41100.00%2100.00%
Total41100.00%2100.00%

EXPORT_SYMBOL(deactivate_super); /** * grab_super - acquire an active reference * @s: reference we are trying to make active * * Tries to acquire an active reference. grab_super() is used when we * had just found a superblock in super_blocks or fs_type->fs_supers * and want to turn it into a full-blown active reference. grab_super() * is called with sb_lock held and drops it. Returns 1 in case of * success, 0 if we had failed (superblock contents was already dead or * dying when grab_super() had been called). Note that this is only * called for superblocks not in rundown mode (== ones still on ->fs_supers * of their type), so increment of ->s_count is OK here. */
static int grab_super(struct super_block *s) __releases(sb_lock) { s->s_count++; spin_unlock(&sb_lock); down_write(&s->s_umount); if ((s->s_flags & MS_BORN) && atomic_inc_not_zero(&s->s_active)) { put_super(s); return 1; } up_write(&s->s_umount); put_super(s); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
linus torvaldslinus torvalds4152.56%125.00%
al viroal viro3342.31%250.00%
josh triplettjosh triplett45.13%125.00%
Total78100.00%4100.00%

/* * trylock_super - try to grab ->s_umount shared * @sb: reference we are trying to grab * * Try to prevent fs shutdown. This is used in places where we * cannot take an active reference but we need to ensure that the * filesystem is not shut down while we are working on it. It returns * false if we cannot acquire s_umount or if we lose the race and * filesystem already got into shutdown, and returns true with the s_umount * lock held in read mode in case of success. On successful return, * the caller must drop the s_umount lock when done. * * Note that unlike get_super() et.al. this one does *not* bump ->s_count. * The reason why it's safe is that we are OK with doing trylock instead * of down_read(). There's a couple of places that are OK with that, but * it's very much not a general-purpose interface. */
bool trylock_super(struct super_block *sb) { if (down_read_trylock(&sb->s_umount)) { if (!hlist_unhashed(&sb->s_instances) && sb->s_root && (sb->s_flags & MS_BORN)) return true; up_read(&sb->s_umount); } return false; }

Contributors

PersonTokensPropCommitsCommitProp
dave chinnerdave chinner4474.58%133.33%
al viroal viro813.56%133.33%
konstantin khlebnikovkonstantin khlebnikov711.86%133.33%
Total59100.00%3100.00%

/** * generic_shutdown_super - common helper for ->kill_sb() * @sb: superblock to kill * * generic_shutdown_super() does all fs-independent work on superblock * shutdown. Typical ->kill_sb() should pick all fs-specific objects * that need destruction out of superblock, call generic_shutdown_super() * and release aforementioned objects. Note: dentries and inodes _are_ * taken care of and do not need specific handling. * * Upon calling this function, the filesystem may no longer alter or * rearrange the set of dentries belonging to this super_block, nor may it * change the attachments of dentries to inodes. */
void generic_shutdown_super(struct super_block *sb) { const struct super_operations *sop = sb->s_op; if (sb->s_root) { shrink_dcache_for_umount(sb); sync_filesystem(sb); sb->s_flags &= ~MS_ACTIVE; fsnotify_unmount_inodes(sb); cgroup_writeback_umount(); evict_inodes(sb); if (sb->s_dio_done_wq) { destroy_workqueue(sb->s_dio_done_wq); sb->s_dio_done_wq = NULL; } if (sop->put_super) sop->put_super(sb); if (!list_empty(&sb->s_inodes)) { printk("VFS: Busy inodes after unmount of %s. " "Self-destruct in 5 seconds. Have a nice day...\n", sb->s_id); } } spin_lock(&sb_lock); /* should be initialized for __put_super_and_need_restart() */ hlist_del_init(&sb->s_instances); spin_unlock(&sb_lock); up_write(&sb->s_umount); }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro10572.92%433.33%
christoph hellwigchristoph hellwig2114.58%18.33%
dave jonesdave jones53.47%18.33%
neil brownneil brown42.78%18.33%
tejun heotejun heo32.08%18.33%
david howellsdavid howells32.08%18.33%
kirill korotaevkirill korotaev10.69%18.33%
jan karajan kara10.69%18.33%
josef 'jeff' sipekjosef 'jeff' sipek10.69%18.33%
Total144100.00%12100.00%

EXPORT_SYMBOL(generic_shutdown_super); /** * sget - find or create a superblock * @type: filesystem type superblock should belong to * @test: comparison callback * @set: setup callback * @flags: mount flags * @data: argument to each of them */
struct super_block *sget(struct file_system_type *type, int (*test)(struct super_block *,void *), int (*set)(struct super_block *,void *), int flags, void *data) { struct super_block *s = NULL; struct super_block *old; int err; retry: spin_lock(&sb_lock); if (test) { hlist_for_each_entry(old, &type->fs_supers, s_instances) { if (!test(old, data)) continue; if (!grab_super(old)) goto retry; if (s) { up_write(&s->s_umount); destroy_super(s); s = NULL; } return old; } } if (!s) { spin_unlock(&sb_lock); s = alloc_super(type, flags); if (!s) return ERR_PTR(-ENOMEM); goto retry; } err = set(s, data); if (err) { spin_unlock(&sb_lock); up_write(&s->s_umount); destroy_super(s); return ERR_PTR(err); } s->s_type = type; strlcpy(s->s_id, type->name, sizeof(s->s_id)); list_add_tail(&s->s_list, &super_blocks); hlist_add_head(&s->s_instances, &type->fs_supers); spin_unlock(&sb_lock); get_filesystem(type); register_shrinker(&s->s_shrink); return s; }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro22078.29%541.67%
andrew mortonandrew morton186.41%18.33%
li zefanli zefan186.41%18.33%
dave chinnerdave chinner82.85%18.33%
matthias kaehlckematthias kaehlcke72.49%18.33%
david howellsdavid howells51.78%18.33%
ingo molnaringo molnar31.07%18.33%
kirill korotaevkirill korotaev20.71%18.33%
Total281100.00%12100.00%

EXPORT_SYMBOL(sget);
void drop_super(struct super_block *sb) { up_read(&sb->s_umount); put_super(sb); }

Contributors

PersonTokensPropCommitsCommitProp
linus torvaldslinus torvalds23100.00%4100.00%
Total23100.00%4100.00%

EXPORT_SYMBOL(drop_super); /** * iterate_supers - call function for all active superblocks * @f: function to call * @arg: argument to pass to it * * Scans the superblock list and calls given function, passing it * locked superblock and given argument. */
void iterate_supers(void (*f)(struct super_block *, void *), void *arg) { struct super_block *sb, *p = NULL; spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root && (sb->s_flags & MS_BORN)) f(sb, arg); up_read(&sb->s_umount); spin_lock(&sb_lock); if (p) __put_super(p); p = sb; } if (p) __put_super(p); spin_unlock(&sb_lock); }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro13997.89%480.00%
nick pigginnick piggin32.11%120.00%
Total142100.00%5100.00%

/** * iterate_supers_type - call function for superblocks of given type * @type: fs type * @f: function to call * @arg: argument to pass to it * * Scans the superblock list and calls given function, passing it * locked superblock and given argument. */
void iterate_supers_type(struct file_system_type *type, void (*f)(struct super_block *, void *), void *arg) { struct super_block *sb, *p = NULL; spin_lock(&sb_lock); hlist_for_each_entry(sb, &type->fs_supers, s_instances) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root && (sb->s_flags & MS_BORN)) f(sb, arg); up_read(&sb->s_umount); spin_lock(&sb_lock); if (p) __put_super(p); p = sb; } if (p) __put_super(p); spin_unlock(&sb_lock); }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro136100.00%3100.00%
Total136100.00%3100.00%

EXPORT_SYMBOL(iterate_supers_type); /** * get_super - get the superblock of a device * @bdev: device to get the superblock for * * Scans the superblock list and finds the superblock of the file system * mounted on the device given. %NULL is returned if no match is found. */
struct super_block *get_super(struct block_device *bdev) { struct super_block *sb; if (!bdev) return NULL; spin_lock(&sb_lock); rescan: list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_bdev == bdev) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); /* still alive? */ if (sb->s_root && (sb->s_flags & MS_BORN)) return sb; up_read(&sb->s_umount); /* nope, got unmounted */ spin_lock(&sb_lock); __put_super(sb); goto rescan; } } spin_unlock(&sb_lock); return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro7354.89%541.67%
kirill korotaevkirill korotaev2720.30%18.33%
linus torvaldslinus torvalds2518.80%433.33%
pre-gitpre-git86.02%216.67%
Total133100.00%12100.00%

EXPORT_SYMBOL(get_super); /** * get_super_thawed - get thawed superblock of a device * @bdev: device to get the superblock for * * Scans the superblock list and finds the superblock of the file system * mounted on the device. The superblock is returned once it is thawed * (or immediately if it was not frozen). %NULL is returned if no match * is found. */
struct super_block *get_super_thawed(struct block_device *bdev) { while (1) { struct super_block *s = get_super(bdev); if (!s || s->s_writers.frozen == SB_UNFROZEN) return s; up_read(&s->s_umount); wait_event(s->s_writers.wait_unfrozen, s->s_writers.frozen == SB_UNFROZEN); put_super(s); } }

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PersonTokensPropCommitsCommitProp
jan karajan kara74100.00%2100.00%
Total74100.00%2100.00%

EXPORT_SYMBOL(get_super_thawed); /** * get_active_super - get an active reference to the superblock of a device * @bdev: device to get the superblock for * * Scans the superblock list and finds the superblock of the file system * mounted on the device given. Returns the superblock with an active * reference or %NULL if none was found. */
struct super_block *get_active_super(struct block_device *bdev) { struct super_block *sb; if (!bdev) return NULL; restart: spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_bdev == bdev) { if (!grab_super(sb)) goto restart; up_write(&sb->s_umount); return sb; } } spin_unlock(&sb_lock); return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
christoph hellwigchristoph hellwig6265.26%116.67%
al viroal viro3334.74%583.33%
Total95100.00%6100.00%


struct super_block *user_get_super(dev_t dev) { struct super_block *sb; spin_lock(&sb_lock); rescan: list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_dev == dev) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); /* still alive? */ if (sb->s_root && (sb->s_flags & MS_BORN)) return sb; up_read(&sb->s_umount); /* nope, got unmounted */ spin_lock(&sb_lock); __put_super(sb); goto rescan; } } spin_unlock(&sb_lock); return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
al viroal viro7460.16%541.67%
kirill korotaevkirill korotaev2721.95%18.33%
linus torvaldslinus torvalds129.76%325.00%
pre-gitpre-git108.13%325.00%
Total123100.00%12100.00%

/** * do_remount_sb - asks filesystem to change mount options. * @sb: superblock in question * @flags: numeric part of options * @data: the rest of options * @force: whether or not to force the change * * Alters the mount options of a mounted file system. */
int do_remount_sb(struct super_block *sb, int flags, void *data, int force) { int retval; int remount_ro; if (sb->s_writers.frozen != SB_UNFROZEN) return -EBUSY; #ifdef CONFIG_BLOCK if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) return -EACCES; #endif remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); if (remount_ro) { if (!hlist_empty(&sb->s_pins)) { up_write(&sb->s_umount); group_pin_kill(&sb->s_pins); down_write(&sb->s_umount); if (!sb->s_root) return 0; if (sb->s_writers.frozen != SB_UNFROZEN) return -EBUSY; remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); } } shrink_dcache_sb(sb); /* If we are remounting RDONLY and current sb is read/write, make sure there are no rw files opened */ if (remount_ro) { if (force) { sb->s_readonly_remount = 1; smp_wmb(); } else { retval = sb_prepare_remount_readonly(sb); if (retval) return retval; } } if (sb->s_op->remount_fs) { retval = sb->s_op->remount_fs(sb, &flags, data); if (retval) { if (!force) goto cancel_readonly; /* If forced remount, go ahead despite any errors */ WARN(1, "forced remount of a %s fs returned %i\n", sb->s_type->name, retval); } } sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); /* Needs to be ordered wrt mnt_is_readonly() */ smp_wmb(); sb->s_readonly_remount = 0; /* * Some filesystems modify their metadata via some other path than the * bdev buffer cache (eg. use a private mapping, or directories in * pagecache, etc). Also file data modifications go via their own * mappings. So If we try to mount readonly then copy the filesystem * from bdev, we could get stale data, so invalidate it to give a best * effort at coherency. */ if (remount_ro && sb->s_bdev) invalidate_bdev(sb->s_bdev); return 0; cancel_readonly: sb->s_readonly_remount = 0; return retval; }

Contributors

PersonTokensPropCommitsCommitProp
linus torvaldslinus torvalds10732.92%210.00%
al viroal viro8626.46%420.00%
miklos szeredimiklos szeredi6620.31%210.00%
nick pigginnick piggin247.38%15.00%
andrew mortonandrew morton113.38%15.00%
christoph hellwigchristoph hellwig113.38%15.00%
pre-gitpre-git103.08%630.00%
david howellsdavid howells51.54%15.00%
jan karajan kara51.54%210.00%
Total325100.00%20100.00%


static void do_emergency_remount(struct work_struct *work) { struct super_block *sb, *p = NULL; spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; sb->s_count++; spin_unlock(&sb_lock); down_write(&sb->s_umount); if (sb->s_root && sb->s_bdev && (sb->s_flags & MS_BORN) && !(sb->s_flags & MS_RDONLY)) {