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[PATCH] Clean up expand_fdtable() and expand_files()

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Perform a code cleanup against the expand_fdtable() and expand_files()
functions inside fs/file.c.  It aims to make the flow of code within these
functions simpler and easier to understand, via added comments and modest
refactoring.

Signed-off-by: Vadim Lobanov <vlobanov@speakeasy.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Vadim Lobanov 2006-09-29 02:01:43 -07:00 committed by Linus Torvalds
parent 3706baa8b1
commit 74d392aaab
1 changed files with 35 additions and 41 deletions
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76
fs/file.c
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@ -288,71 +288,65 @@ static struct fdtable *alloc_fdtable(int nr)
}
/*
* Expands the file descriptor table - it will allocate a new fdtable and
* both fd array and fdset. It is expected to be called with the
* files_lock held.
* Expand the file descriptor table.
* This function will allocate a new fdtable and both fd array and fdset, of
* the given size.
* Return <0 error code on error; 1 on successful completion.
* The files->file_lock should be held on entry, and will be held on exit.
*/
static int expand_fdtable(struct files_struct *files, int nr)
__releases(files->file_lock)
__acquires(files->file_lock)
{
int error = 0;
struct fdtable *fdt;
struct fdtable *nfdt = NULL;
struct fdtable *new_fdt, *cur_fdt;
spin_unlock(&files->file_lock);
nfdt = alloc_fdtable(nr);
if (!nfdt) {
error = -ENOMEM;
spin_lock(&files->file_lock);
goto out;
}
new_fdt = alloc_fdtable(nr);
spin_lock(&files->file_lock);
fdt = files_fdtable(files);
if (!new_fdt)
return -ENOMEM;
/*
* Check again since another task may have expanded the
* fd table while we dropped the lock
* Check again since another task may have expanded the fd table while
* we dropped the lock
*/
if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
copy_fdtable(nfdt, fdt);
cur_fdt = files_fdtable(files);
if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
/* Continue as planned */
copy_fdtable(new_fdt, cur_fdt);
rcu_assign_pointer(files->fdt, new_fdt);
free_fdtable(cur_fdt);
} else {
/* Somebody expanded while we dropped file_lock */
/* Somebody else expanded, so undo our attempt */
spin_unlock(&files->file_lock);
__free_fdtable(nfdt);
__free_fdtable(new_fdt);
spin_lock(&files->file_lock);
goto out;
}
rcu_assign_pointer(files->fdt, nfdt);
free_fdtable(fdt);
out:
return error;
return 1;
}
/*
* Expand files.
* Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked.
* Should be called with the files->file_lock spinlock held for write.
* This function will expand the file structures, if the requested size exceeds
* the current capacity and there is room for expansion.
* Return <0 error code on error; 0 when nothing done; 1 when files were
* expanded and execution may have blocked.
* The files->file_lock should be held on entry, and will be held on exit.
*/
int expand_files(struct files_struct *files, int nr)
{
int err, expand = 0;
struct fdtable *fdt;
fdt = files_fdtable(files);
if (nr >= fdt->max_fdset || nr >= fdt->max_fds) {
if (fdt->max_fdset >= NR_OPEN ||
fdt->max_fds >= NR_OPEN || nr >= NR_OPEN) {
err = -EMFILE;
goto out;
}
expand = 1;
if ((err = expand_fdtable(files, nr)))
goto out;
}
err = expand;
out:
return err;
/* Do we need to expand? */
if (nr < fdt->max_fdset && nr < fdt->max_fds)
return 0;
/* Can we expand? */
if (fdt->max_fdset >= NR_OPEN || fdt->max_fds >= NR_OPEN ||
nr >= NR_OPEN)
return -EMFILE;
/* All good, so we try */
return expand_fdtable(files, nr);
}
static void __devinit fdtable_defer_list_init(int cpu)